The simple answer is to use conditional formatting.
Conditional formatting allows the cell pattern colour, font and font colour, and borders to be changed based on what is in the cell.
Select the first cell, say A1, then from the toolbar Format-Conditional formatting ...
As a start, use Condition 1 and Cell Value Is
In the second drop-down select a condition, such as between.
Then in the next two cells enter values
select not equal to, which gives you one box to fill and enter =""
Select Format, and create the format you want when the cell meets your conditions.
The second option (not equal to / ="") will cause the cell to use the conditional format whenever there is an entry in the cell.
Now select the cell with the conditional formatting, and Copy it.
Select the cells you are going to use on your worksheet and PasteSpecial - Formats.
I suggest that you PasteSpecial only to the cells you are going to use, not to the full worksheet (remember there are over 65,000 rows on an Excel 2003 worksheet and 256 columns).
In Excel 2003, you can have up to three different formats for each cell and the formats can depend on more complex formulas and on the values of other cells, so there are lots of options.